Transfer laminate for optical film

Abstract

The present invention relates to a transfer laminate for an optical film, the transfer laminate comprising a substrate, an alignment film, and a vertically aligned liquid crystal film in the given order. The polar term of surface free energy of the alignment film is 1.0 mJ / m2 or greater, and the silicone-based surfactant content of the alignment film is less than 1.5 parts by mass with respect to 100 parts by mass of a resin in the alignment film. The vertically aligned liquid crystal film contains a silicone-based surfactant at a proportion of 0.3 to 4.0 parts by mass with respect to 100 parts by mass of a liquid crystal compound in the vertically aligned liquid crystal film.

Description

Transfer laminate for optical film

[0001] This invention relates to a transfer laminate for optical films.

[0002] In recent years, optical films used in flat panel displays and the like have been known that have a liquid crystal film made by curing liquid crystal material in an oriented state. Methods for manufacturing such optical films include directly forming the liquid crystal film on a desired substrate and a transfer method. The transfer method, for example, involves forming a liquid crystal film on a releaseable support in a peelable state to create a transfer laminate, adhering and laminating it to a desired substrate (transfer target), and then peeling off the support to form a liquid crystal film on the desired substrate.

[0003] When transferring the transfer laminate to the target object, if the peelability at the peel interface of the transfer laminate is insufficient, transfer defects can occur, such as parts of the transfer laminate that should not be transferred being transferred to the target object (separation). In particular, the impact of transfer defects becomes a concern as the peeling speed increases in order to improve the productivity of optical films.

[0004] Patent Document 1 describes a transfer laminate for optical films having a substrate, an alignment film for aligning liquid crystal compounds, and a phase difference layer (liquid crystal film), and discloses a technique for incorporating a fluorine-containing surfactant into the alignment film to suppress transfer defects.

[0005] Japanese Patent Application Publication No. 2015-148745

[0006] The peeling interface of the transfer laminate for optical films described in Patent Document 1 is the interface between the substrate and the alignment film, and the alignment film is peeled off together with the liquid crystal film and transferred to the transfer target. As a result, the thickness of the transferred layer is generally large, about 2 to 4 μm, making it unsuitable for optical film applications where thinness is required.

[0007] The present invention aims to provide a transfer laminate for optical films that exhibits excellent peelability and good liquid crystal orientation.

[0008] The present invention relates to the following transfer laminate for optical films: A transfer laminate for optical films comprising, in this order, a substrate, an alignment film, and a vertically aligned liquid crystal film, wherein the polarity term of the surface free energy of the alignment film is 1.0 mJ / m ２ The above is true, wherein the content of the silicone-based surfactant in the alignment film is less than 1.5 parts by mass per 100 parts by mass of resin in the alignment film, and the vertically aligned liquid crystal film contains the silicone-based surfactant in a ratio of 0.3 to 4.0 parts by mass per 100 parts by mass of liquid crystal compound in the vertically aligned liquid crystal film, in a transfer laminate for optical film.

[0009] The transfer laminate for optical films according to the present invention exhibits good liquid crystal orientation and excellent peelability, thus suppressing transfer defects even at high peeling speeds during transfer to the substrate. Furthermore, since the transfer laminate for optical films according to the present invention is peelable at the interface between the alignment film and the vertically aligned liquid crystal film, it enables the thinning of optical devices.

[0010] Figure 1 is a cross-sectional view showing the transfer laminate for optical film according to this embodiment.

[0011] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified and implemented as appropriate without departing from the spirit of the invention. Furthermore, the "~" indicating a numerical range is used to mean that the numbers written before and after it are included as the lower limit and upper limit.

[0012] <Transfer Laminate for Optical Film> As shown in Figure 1, the transfer laminate for optical film (hereinafter also referred to as "this transfer laminate") 10 according to an embodiment of the present invention comprises a substrate 1, an alignment film 2, and a vertically aligned liquid crystal film 3 in this order. In this transfer laminate, the interface between the vertically aligned liquid crystal film and the alignment film is a peelable interface. Therefore, by adhering and laminating this transfer laminate to a desired substrate (transfer target), and peeling off the substrate and alignment film, a liquid crystal film can be transferred to the desired substrate to produce an optical film.

[0013] In this transfer laminate with the above configuration, the polarity term of the surface free energy of the orientation film is 1.0 mJ / m ２As described above, by having a silicone-based surfactant content in the alignment film of less than 1.5 parts by mass per 100 parts by mass of resin in the alignment film, and by having the vertically aligned liquid crystal film contain a silicone-based surfactant in a ratio of 0.3 to 4.0 parts by mass per 100 parts by mass of liquid crystal compound in the vertically aligned liquid crystal film, a transfer laminate with excellent peelability and good liquid crystal film orientation can be provided. Furthermore, with a transfer laminate having such a configuration, the peelability is excellent even if the alignment film does not contain fluorine, so transfer defects can be suppressed even if the peeling speed is high when transferring to the transfer target.

[0014] (Substrate) In this transfer laminate, the substrate functions as a support for the alignment film and the vertically aligned liquid crystal film. Specifically, examples of substrates include glass substrates and resin substrates, but resin substrates are preferred from the viewpoint of processability. When a UV-curable resin is used for the alignment film described later, the substrate is preferably UV-transparent.

[0015] Examples of resins constituting the resin substrate include polyolefins such as polyethylene, polypropylene, and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylate esters; polyacrylic acid esters; cellulose esters such as triacetylcellulose, diacetylcellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyetherketone; polyphenylene sulfide and polyphenylene oxide. Such resins can be used to form films of the substrate by known means such as solvent casting and melt extrusion. Furthermore, these resin substrates may be uniaxially stretched or biaxially stretched films, or films that have undergone surface treatments such as easy adhesion or easy peelability. After the liquid crystal film is transferred, the substrate is discarded together with the alignment film, so from the viewpoint of cost reduction, inexpensive resins such as polyethylene terephthalate are preferred.

[0016] The thickness of the base material is not particularly limited, but it is preferably in the range of 1 to 200 μm, more preferably 10 to 150 μm, and particularly preferably 20 to 100 μm. If it is 1 μm or more, it is preferable because the self-supporting property as a base material can be maintained. If it is 200 μm or less, it is preferable because coating by a roll-to-roll method is possible.

[0017] (Alignment film) In this transfer laminate, the alignment film has a function of aligning (arranging) liquid crystal compounds in a predetermined direction (in one aspect of this embodiment, the direction perpendicular to the main surface of the laminate).

[0018] In this transfer laminate, the polar term of the surface free energy of the alignment film is 1.0 mJ / m ２ or more. The surface free energy is mainly an index of the surface polarity, and among them, the polar term has a large correlation with the surface polarity. When the polar term is 1.0 mJ / m ２ or more, the liquid crystal alignment property of the liquid crystal film can be enhanced. The polar term is preferably 1.5 mJ / m ２ or more, and more preferably 2.0 mJ / m ２ or more. The upper limit is not limited, but for example, it is 10 mJ / m ２ or less.

[0019] The surface free energy (γs ｖ : unit, mJ / m ２ ), the dispersion term (γs ｄ ), and the polar term (γs ｈ ) can be experimentally obtained using the contact angles of pure water and methylene iodide on each surface of the alignment film to be measured, as described in Japanese Patent No. 6479824. For example, referring to D. K. Owens: J. Appl. Polym. Sci., 13, 1741 (1969). At this time, taking the contact angles of pure water and methylene iodide as θ Ｈ２Ｏ and θ ＣＨ２Ｉ２ respectively, the dispersion term (γs ｄ ) and the polar term (γs ｈ ) are obtained by the following simultaneous equations (A) and (B). The surface free energy is the value γs ｖ (= γs ｄ + γs ｈ ). 1 + cosθＨ２Ｏ = 2√γs ｄ (√γ Ｈ２Ｏ ｄ / γ Ｈ２Ｏ ｖ ) + 2√γs ｈ (√γ Ｈ２Ｏ ｈ / γ Ｈ２Ｏ ｖ )...(A) 1+cosθ ＣＨ２Ｉ２ = 2√γs ｄ (√γ ＣＨ２Ｉ２ ｄ / γ ＣＨ２Ｉ２ ｖ ) + 2√γs ｈ (√γ ＣＨ２Ｉ２ ｈ / γ ＣＨ２Ｉ２ ｖ ) ... (B) (However, γ Ｈ２Ｏ ｄ = 21.8, γ Ｈ２Ｏ ｈ = 51.0, γ Ｈ２Ｏ ｖ = 72.8, γ ＣＨ２Ｉ２ ｄ = 49.5, γ ＣＨ２Ｉ２ ｈ = 1.3, γ ＣＨ２Ｉ２ ｖ (Let's assume it's 50.8.)

[0020] In order to set the polarity term of the surface free energy of the alignment film within the above range, for example, the following can be done: using acrylic monomers as the monomers constituting the alignment film (as described later); the alignment film containing a silicone surfactant (as described later); using a silicone-based surfactant modified with polar functional groups as described later; and modifying the surface of the alignment film (e.g., corona treatment or plasma treatment).

[0021] The orientation film is preferably composed of a cured product of an orientation film composition containing an orientation component that exhibits vertical orientation. Here, as the orientation component, acrylic monomers are preferred, and acrylate monomers are more preferred, from the viewpoint of exhibiting vertical orientation and from the viewpoint of increasing the polarity term of the surface free energy of the orientation film. The acrylate monomer may be a monofunctional acrylate monomer or a polyfunctional acrylate monomer.

[0022] Examples of monofunctional acrylate monomers include urethane acrylate, isoboronyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, isostearyl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, lauryl acrylate, isooctyl acrylate, tetrahydrofurfuryl acrylate, behenyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, n-hexyl acrylate, and cyclohexyl acrylate.

[0023] Examples of polyfunctional acrylate monomers include urethane acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerin triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, hydroxypiperic acid ester neopentyl glycol diacrylate, and the like.

[0024] The above acrylate monomers may be used in combination of one or more types. In particular, from the viewpoint of increasing the polarity term of the surface free energy of the orientation film, it is preferable to include monofunctional or polyfunctional urethane acrylate.

[0025] The acrylate monomer content in the alignment film composition is not particularly limited as long as it can vertically align the liquid crystal compound described later, but it is preferably 50 to 99% by mass.

[0026] In this transfer laminate, the alignment film preferably contains a silicone-based surfactant. This makes it easier to obtain an alignment film in which the polarity term of the surface free energy falls within the above range. The polar ends of the vertically aligned liquid crystal film interact electrostatically with the surfactant, making it easier for the liquid crystal compound to align vertically and improving the liquid crystal alignment. Furthermore, the adhesion force with the vertically aligned liquid crystal film can be reduced, thereby improving peelability. However, from the viewpoint of maintaining good liquid crystal alignment and peelability, when the alignment film contains a silicone-based surfactant, the content of the silicone-based surfactant in the alignment film is less than 1.5 parts by mass, preferably 1.0 part by mass or less, and more preferably 0.5 parts by mass or less, per 100 parts by mass of resin in the alignment film. Here, the resin in the alignment film is a polymer of monomers in the alignment film composition. When the above content of the silicone-based surfactant is converted to the content in the alignment film, it is less than 1.48% by mass, preferably 0.99% by mass or less, and more preferably 0.50% by mass or less.

[0027] Examples of silicone-based surfactants include low molecular weight compounds containing silicon atoms, such as polymethylphenylsiloxane, polyether-modified silicone oil, polyethylene glycol-modified silicone oil, polypropylene glycol-modified silicone oil, polyether-modified dimethylpolysiloxane, dimethyl silicone, diphenyl silicone, hydrogen-modified polysiloxane, vinyl-modified polysiloxane, hydroxy-modified polysiloxane, amino-modified polysiloxane, carboxyl-modified polysiloxane, ester-modified polysiloxane, epoxy-modified polysiloxane, methacryloxy-modified polysiloxane, mercapto-modified polysiloxane, long-chain alkyl-modified polysiloxane, phenyl-modified polysiloxane, and silicone-modified copolymers.

[0028] As a silicone-based surfactant, it is preferable that it is modified with a polar functional group from the viewpoint of increasing the polar term of the surface free energy. Preferred such silicone-based surfactants are those modified with polar polymers such as polyethers, polyethylene glycol, and polypropylene glycol, and silicone-based surfactants in which polar functional groups such as amino groups, carboxyl groups, hydroxyl groups, ester groups, ether groups, and amide groups are introduced into the silicone molecule. If a silicone-based surfactant has a polar polymer or a polar functional group, it is easier to obtain an oriented film in which the polar term of the surface free energy falls within the above range.

[0029] The alignment film is obtained by curing the alignment film composition. In addition to the components described above, the alignment film composition may contain other components as long as they do not impair the effects of the present invention. Other components may include, for example, adhesion-enhancing components to improve adhesion to the substrate. This is preferable because it improves the adhesion between the substrate and the alignment film, thus preventing transfer defects such as the alignment film being transferred to the object to be transferred during transfer. Examples of adhesion-enhancing components include acrylamide monomers when the alignment film composition contains acrylate monomers. The content of the adhesion-enhancing component in the alignment film composition is preferably 0.1 to 30% by mass in terms of solid content.

[0030] The oriented film composition preferably further contains a solvent capable of dissolving the above-mentioned components and a polymerization initiator necessary for curing.

[0031] Examples of solvents include, but are not limited to, hydrocarbon solvents such as benzene and hexane; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether solvents such as tetrahydrofuran, 1,2-dimethoxyethane, and propylene glycol monoethyl ether; alkyl halide solvents such as chloroform and dichloromethane; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate; amide solvents such as N,N-dimethylformamide; sulfoxide solvents such as dimethyl sulfoxide; ane solvents such as cyclohexane; and alcohol solvents such as methanol, ethanol, and isopropyl alcohol. Furthermore, the solvent may be a single solvent or a mixture of two or more solvents.

[0032] As the polymerization initiator, a photopolymerization initiator is preferred, and examples include benzoin-based, phenone-based, and anthraquinone-based polymerization initiators. The content of the polymerization initiator is preferably in the range of 0.1 to 5 parts by mass per 100 parts by mass of the monomer to be cured.

[0033] In this transfer laminate, the thickness of the alignment film is preferably 0.1 to 20 μm, and more preferably 0.5 to 10 μm. If the thickness of the alignment film is within the above range, it becomes easier to avoid coating defects caused by scratches on the substrate or foreign matter adhering to the substrate. Furthermore, it is possible to suppress deterioration of the orientation of the vertically aligned liquid crystal film due to foreign matter (bleed-out material) that may be generated by the bleed-out phenomenon from the substrate. In addition, when this transfer laminate is manufactured by a roll-to-roll method, for example, it is possible to suppress a decrease in yield due to the occurrence of cracks during the conveying and winding processes during manufacturing.

[0034] This transfer laminate exhibits excellent peelability even without the fluorine-containing orientation film. Furthermore, since many fluorine-containing compounds have been confirmed to be difficult to decompose, have long-distance mobility in the environment, and exhibit bioaccumulation and adverse effects on human health, there has been a growing demand in recent years to avoid using fluorine-containing compounds in the constituent materials of various components. Therefore, it is preferable that the orientation film in this transfer laminate does not contain fluorine. Note that "fluorine-free" means substantially free of fluorine, and does not exclude unavoidable fluorine content. More specifically, the elemental fluorine content is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0% by mass.

[0035] (Vertical Alignment Liquid Crystal Film) In this transfer laminate, the vertical alignment liquid crystal film contains a liquid crystal compound that exhibits liquid crystal properties. The liquid crystal compound has refractive index anisotropy and has the function of imparting a desired phase difference by being regularly arranged.

[0036] Examples of liquid crystalline compounds include compounds having highly rigid moieties (mesogens) that exhibit liquid crystalline properties. Mesogens include, for example, substructures having two or more ring structures, preferably three or more ring structures, where the ring structures are directly linked by bonds or where the ring structures are linked by one to three atoms. The ring structures may be aromatic rings such as benzene, naphthalene, and anthracene, or cyclic aliphatic hydrocarbons such as cyclopentane and cyclohexane.

[0037] Furthermore, it is preferable that the liquid crystal compound is oriented perpendicular to the main surface of the laminate (the film surface in the case of an optical film). This perpendicular orientation of the liquid crystal compound is preferable because it facilitates the expression of functions such as improving the viewing angle of the optical device. "Perpendicular orientation" means that the average angle between the film surface and the molecular axis of the liquid crystal compound along its long axis is in the range of 70 to 90 degrees, preferably 80 to 90 degrees, and more preferably 85 to 90 degrees. The liquid crystal phase may be either a nematic phase or a smectic phase.

[0038] As for liquid crystalline compounds, rod-shaped liquid crystal compounds are preferred from the viewpoint of easily obtaining vertical orientation. Preferred examples of rod-shaped liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyanosubstituted phenylpyrimidines, alkoxysubstituted phenylpyrimidines, phenyldioxanes, trans, and alkenylcyclohexylbenzonitriles. In addition to the low molecular weight liquid crystal compounds described above, high molecular weight liquid crystal compounds can also be used.

[0039] Furthermore, as a liquid crystal compound, it is preferable to include a component having a polar group at its terminal end that enhances electrostatic interaction with the alignment film, from the viewpoint of improving vertical alignment. Specific examples of polar groups include -Cl, -CN, -NCO, -NCS, and -NO ２ , -NHC(=O)-R', -C(=O)-OR', -OH, -SH, -CHO, -SO ３ H, -NR' ２ Examples include -R'' or -OR'' (where R' is a hydrogen atom or hydrocarbon group, and R'' is an alkyl group). Furthermore, the proportion of liquid crystal compounds having the above polar groups at their ends is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass, of the total liquid crystal compounds in the liquid crystal film.

[0040] The orientation of the liquid crystal compound is more preferably fixed by polymerization. The liquid crystal compound preferably has a substructure that can undergo polymerization or crosslinking reactions by active light, electron beams, heat, etc., and more preferably has a polymerizable group. Examples of polymerizable groups include radical polymerizable functional groups and cationic polymerizable functional groups. Representative examples of radical polymerizable functional groups include functional groups having at least one addition polymerizable ethylenically unsaturated double bond, such as vinyl groups with or without substituents, acrylate groups (a general term encompassing acryloyl groups, methacryloyl groups, acryloyloxy groups, and methacryloyloxy groups). Specific examples of cationic polymerizable functional groups include epoxy groups. Other examples of polymerizable functional groups include isocyanate groups and unsaturated triple bonds. Among these, functional groups having ethylenically unsaturated double bonds are preferably used from a process standpoint. As polymerizable rod-shaped liquid crystal compounds, compounds described in Japanese Patent Publication No. 2019-204083, etc., can be used.

[0041] Furthermore, the liquid crystal compound may be used alone or in combination of two or more. When using a single compound, it is preferable that it is a polymerizable liquid crystal compound having two or more crosslinking sites. When using two or more compounds in combination, it is preferable that at least one of them is a polymerizable liquid crystal compound having two or more crosslinking sites. Moreover, it is preferable that at least one of them has a functional group at its end that enhances electrostatic interaction with the alignment film.

[0042] The vertically aligned liquid crystal film contains a silicone-based surfactant. This reduces the adhesion between the alignment film and the liquid crystal film, and improves the peelability of the peel interface between the alignment film and the liquid crystal film. The content of the silicone-based surfactant in the vertically aligned liquid crystal film is 0.3 to 4.0 parts by mass per 100 parts by mass of the liquid crystal compound. This ratio yields a liquid crystal film with good liquid crystal alignment. The content of the silicone-based surfactant is preferably 0.5 to 3.0 parts by mass, more preferably 1.0 to 2.0 parts by mass, per 100 parts by mass of the liquid crystal compound. Furthermore, when the above content of the silicone-based surfactant is converted to the content in the vertically aligned liquid crystal film, it is 0.28 to 3.9% by mass, preferably 0.48 to 2.9% by mass, and more preferably 0.95 to 1.90% by mass.

[0043] Examples of silicone-based surfactants include those similar to those that can be contained in the orientation film. Furthermore, from the viewpoint of vertical orientation, silicone-based surfactants modified with polar functional groups are preferred. Using silicone-based surfactants modified with polar functional groups strengthens the electrostatic interaction with the orientation film, thereby improving vertical orientation. Preferred silicone-based surfactants include those modified with polar polymers such as polyethers, polyethylene glycols, and polypropylene glycols, and silicone-based surfactants in which polar functional groups such as amino groups, carboxyl groups, hydroxyl groups, ester groups, ether groups, and amide groups are introduced into the silicone molecule. Examples of silicone-based surfactants include low molecular weight compounds containing silicon atoms, such as polymethylphenylsiloxane, polyether-modified silicone oil, polyethylene glycol-modified silicone oil, polypropylene glycol-modified silicone oil, polyether-modified dimethylpolysiloxane, dimethyl silicone, diphenyl silicone, hydrogen-modified polysiloxane, vinyl-modified polysiloxane, hydroxy-modified polysiloxane, amino-modified polysiloxane, carboxyl-modified polysiloxane, ester-modified polysiloxane, epoxy-modified polysiloxane, methacryloxy-modified polysiloxane, mercapto-modified polysiloxane, long-chain alkyl-modified polysiloxane, phenyl-modified polysiloxane, and silicone-modified copolymers.

[0044] The oriented liquid crystal compound is fixed while maintaining its orientation. Fixation is preferably carried out by a polymerization reaction, which includes thermal polymerization reactions using a thermal polymerization initiator and photopolymerization reactions using a photopolymerization initiator. Among these, photopolymerization reactions are preferred. Examples of photopolymerization initiators include α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminophenyl ketones, acridine and phenazine compounds, and oxadiazole compounds.

[0045] The polymerization initiator content is preferably in the range of 0.1 to 5.0 parts by mass, and more preferably in the range of 0.2 to 3.0 parts by mass, per 100 parts by mass of the liquid crystal compound.

[0046] When forming a liquid crystal film, the above-mentioned liquid crystal compound is preferably dissolved or dispersed in a solvent as needed, together with a silicone-based surfactant, polymerization initiator, etc. Examples of solvents include, but are not limited to, hydrocarbon solvents such as benzene and hexane, ketone solvents, ether solvents, alkyl halide solvents, ester solvents, amide solvents, sulfoxide solvents, anone solvents, and alcohol solvents. Furthermore, the solvent may be a single type or a mixture of two or more solvents.

[0047] In this transfer laminate, the thickness of the vertically aligned liquid crystal film is appropriately determined depending on the application, for example, 0.01 to 5 μm.

[0048] <Method for Manufacturing Transfer Laminates for Optical Films> The method for manufacturing the transfer laminates described here will be explained. The method for manufacturing the transfer laminates involves coating one main surface of a substrate with an alignment film composition, drying and curing it to form an alignment film, and coating the alignment film with a vertical alignment liquid crystal film composition, drying and curing it to form a vertical alignment liquid crystal film.

[0049] The substrate surface on which the orientation film is formed may be treated for easy adhesion. The orientation film composition includes the orientation component described above, and optionally a silicone-based surfactant, an adhesion-enhancing component, a polymerization initiator, a solvent, etc. The coating method for the orientation film composition is not particularly limited, and for example, die coating, gravure coating, reverse coating, knife coating, dip coating, spray coating, air knife coating, spin coating, roll coating, print coating, immersion and pull-up coating, curtain coating, casting, bar coating, extrusion coating, E-type coating method, etc., can be used.

[0050] The composition for the alignment film can be cured by thermal curing or photocuring.

[0051] The composition for vertically aligned liquid crystal films comprises a liquid crystal compound, a silicone-based surfactant, and optionally a polymerization initiator, a solvent, etc. The coating method for the composition for vertically aligned liquid crystal films is the same as the coating method for the composition for alignment films.

[0052] The composition for vertically aligned liquid crystal films can be cured by thermal curing or photocuring.

[0053] Through the above process, a transfer laminate for optical film is produced in which a substrate, an alignment film, and a vertically aligned liquid crystal film are stacked in that order.

[0054] <Characteristics of the Transfer Laminate for Optical Films> In the transfer laminate for optical films according to this embodiment, the interface between the vertically aligned liquid crystal film and the alignment film is a peelable interface. Preferably, the peel strength when the vertically aligned liquid crystal film is peeled at a peeling speed of 300 mm / min is 1 N / 25 mm or less. As a result, this transfer laminate exhibits excellent peelability even at high peeling speeds, effectively suppressing the occurrence of transfer defects of the transfer laminate to the transfer target, and increasing productivity.

[0055] <Applications of Transfer Laminates for Optical Films> The transfer laminate for optical films according to this embodiment is useful for manufacturing optical films by the transfer method. In a method of manufacturing an optical film by the transfer method using this transfer laminate, the liquid crystal film side of the transfer laminate is transferred and laminated onto a desired substrate (transfer target) such as glass via an adhesive or tack, and then the substrate side of the transfer laminate is peeled off, thereby transferring only the vertically oriented liquid crystal film to the transfer target and manufacturing an optical film.

[0056] As described above, the following is disclosed in this specification: [1] A transfer laminate for optical films comprising a substrate, an alignment film, and a vertically aligned liquid crystal film in this order, wherein the polarity term of the surface free energy of the alignment film is 1.0 mJ / m ２[1] The transfer laminate for optical film, wherein the content of the silicone-based surfactant in the alignment film is less than 1.5 parts by mass per 100 parts by mass of resin in the alignment film, and the vertically aligned liquid crystal film contains the silicone-based surfactant in a ratio of 0.3 to 4.0 parts by mass per 100 parts by mass of liquid crystal compound in the vertically aligned liquid crystal film. [2] The transfer laminate for optical film according to [1], wherein the interface between the vertically aligned liquid crystal film and the alignment film is a peelable interface, and the peel strength when the vertically aligned liquid crystal film is peeled at a peeling speed of 300 mm / min is 1 N / 25 mm or less. [3] The transfer laminate for optical film according to [1] or [2], wherein the fluorine content in the alignment film is 0.1% by mass or less.

[0057] The present invention will be described in more detail below using examples, but the present invention is not limited to these. Examples 1 to 7 are examples, and Examples 8 to 12 are comparative examples.

[0058] <Materials for the base material> PET base material: CosmoShine A4160 manufactured by Toyobo Co., Ltd., film thickness 50 μm

[0059] <Materials for the composition of the orientation film> N,N-dimethylacrylamide: Manufactured by Tokyo Chemical Industry Co., Ltd. Difunctional acrylate: Manufactured by Shin Nakamura Chemical Co., Ltd., A-DCP Polyfunctional urethane acrylate: Manufactured by Shin Nakamura Chemical Co., Ltd., U-6LPA Polyether-modified polysiloxane A: Manufactured by Bic Chemie, BYK-327, polyether ratio (EO: 3.3, PO: 0.6 (normalized by Si content)) Polyether-modified polysiloxane B: Manufactured by Bic Chemie, BYK-333, polyether ratio (EO: 3.7, PO: 0.8 (normalized by Si content)) Polyether-modified polysiloxane C: Manufactured by Bic Chemie, BYK-3760, polyether ratio (EO: 0.9, PO: 0.5 (normalized by Si content)) Polyether-modified polysiloxane D: BYK-330, manufactured by Bic Chemie, polyether ratio (EO: 0, PO: 0.8 (normalized by Si content)) Photopolymerization initiator A: Irgacure 184, manufactured by IGM Resins B. V. Photopolymerization initiator B: Irgacure 907, manufactured by IGM Resins B. V. Solvent: Propylene glycol methyl ether acetate, manufactured by Kanto Chemical Co., Ltd.

[0060] <Materials for liquid crystal film compositions> Liquid crystal compound A: LC242, manufactured by BASF.

[0061]

[0062] Liquid crystal compound B: 4-[(6-acryloyloxy)hexyloxy]-4'-cyanobiphenyl, manufactured by Tokyo Chemical Industry Co., Ltd.

[0063]

[0064] Photopolymerization initiator C: Irgacure OXE01, manufactured by IGM Resins B.V. Solvent: Propylene glycol methyl ether acetate, manufactured by Kanto Chemical Co., Ltd.

[0065] (Example 1) (Preparation of alignment film) The alignment film composition shown in Table 2 is coated onto the easily adhesive surface of an easily adhesive treated PET substrate using a die coater, the solvent is dried in a drying oven at 65°C, and then 1000 mJ / cm² is applied. ２ An oriented film with a thickness of 5 μm was fabricated by irradiation with ultraviolet light. The content of silicone-based surfactant, photopolymerization initiator, and solvent is expressed in parts by mass per 100 parts by mass of the resin (total amount of acrylamide, difunctional acrylate, and polyfunctional urethane acrylate).

[0066] (Preparation of vertically aligned liquid crystal film) The liquid crystal film composition shown in Table 2 is coated onto the alignment film using a die coater, the solvent is dried in a drying oven at 90°C, and then 1000 mJ / cm² is added. ２ A vertically aligned liquid crystal film with a thickness of approximately 0.8 μm was formed by irradiation with ultraviolet light. The content (parts by mass) of the silicone-based surfactant, photopolymerization initiator, and solvent is expressed as parts by mass per 100 parts by mass of the total amount of liquid crystal compounds (A and B).

[0067] Through the above process, a transfer laminate for optical film was fabricated in which a substrate, an alignment film, and a vertically aligned liquid crystal film were stacked in that order.

[0068] (Examples 2-12) Transfer laminates for optical films were prepared in the same manner as in Example 1, except that the composition for the alignment film and the composition for the liquid crystal film were as shown in Table 2.

[0069] <Evaluation> (Surface Free Energy) An alignment film was prepared for evaluating the surface free energy. The method was the same as that in Example 1, except that the types and contents of the silicone-based surfactants were as shown in Table 1. The contact angles of pure water and methylene iodide on the surface of each alignment film were measured. Taking each contact angle as θ Ｈ２Ｏ and θ ＣＨ２Ｉ２ , the dispersion term (γs ｄ ) and the polar term (γs ｈ ) of the alignment film were obtained by the following simultaneous equations (A) and (B). The surface free energy of the alignment film is the value γs ｖ (= γs ｄ + γs ｈ ). 1 + cosθ Ｈ２Ｏ = 2√γs ｄ (√γ Ｈ２Ｏ ｄ / γ Ｈ２Ｏ ｖ ) + 2√γs ｈ (√γ Ｈ２Ｏ ｈ / γ Ｈ２Ｏ ｖ )... (A) 1 + cosθ ＣＨ２Ｉ２ = 2√γs ｄ (√γ ＣＨ２Ｉ２ ｄ / γ ＣＨ２Ｉ２ ｖ ) + 2√γs ｈ (√γ ＣＨ２Ｉ２ ｈ / γ ＣＨ２Ｉ２ ｖ )... (B) (However, γ Ｈ２Ｏ ｄ = 21.8, γ Ｈ２Ｏ ｈ = 51.0, γ Ｈ２Ｏ ｖ = 72.8, γ ＣＨ２Ｉ２ ｄ = 49.5, γ ＣＨ２Ｉ２ ｈ = 1.3, γ ＣＨ２Ｉ２ ｖ(Assume = 50.8.) The contact angle was measured using a contact angle meter after conditioned for more than 2 hours in an environment of 20°C to 27°C and 50°C to 65% relative humidity, and then in an environment of 25°C and 60% relative humidity. Table 1 shows the relationship between the type and content of silicone-based surfactants in the orientation film and the surface free energy.

[0070] (Peelability Evaluation) After corona treatment was performed on the vertically aligned liquid crystal film side of the transfer laminate for optical film, it was bonded to a glass measuring 12 cm (length) x 10 cm (width) x 0.7 mm (thickness) via a 15 μm thick pressure-sensitive adhesive manufactured by Lintec Corporation (composition: substrate / alignment film / vertically aligned liquid crystal film / adhesive layer / glass). A 2.5 cm wide cut was made in the obtained sample from the substrate side using a cutter. The prepared sample was set in a Shimadzu Corporation Autograph "EZ-L" and the peeling force was confirmed when peeling off the 2.5 cm wide substrate at a speed of 300 mm / min in a direction parallel to the glass surface. The peeling occurred at the interface between the alignment film and the vertically aligned liquid crystal film. The evaluation was based on the following criteria, with A being considered good. (Evaluation Criteria) A: Peeling force of 1 N / 25 mm or less (good) C: Peeling force greater than 1 N / 25 mm

[0071] (Orientation Evaluation) Similar to the peelability evaluation, measurement samples were prepared consisting of a substrate, alignment film, vertically aligned liquid crystal film, adhesive layer, and glass. Subsequently, the substrate and alignment film were peeled off to obtain a sample for orientation evaluation (composition: vertically aligned liquid crystal film / adhesive layer / glass). Next, the orientation was determined by the brightness when the sample for orientation evaluation was inserted between commercially available polarizing plates arranged in crossed nicols on a backlight. The brightness when nothing was inserted between the polarizing plates was 0.11 cd / m². ２ The results were as follows. Evaluation was based on the following criteria, with A or B indicating good performance. (Evaluation Criteria) A: Brightness of 0.12 cd / m² ２ Less than B: Brightness is 0.12 cd / m² ２ Above, 0.15 cd / m ２ Less than C: Brightness of 0.15 cd / m² ２ That's all.

[0072] The evaluation results are shown in Table 2. Note that the percentages in Table 2 represent mass percentages.

[0073]

[0074]

[0075] From the above results, it can be seen that the transfer laminates for optical films in Examples 1 to 7 are excellent in both peelability and liquid crystal alignment. In the transfer laminate for optical film in Example 8, the polarity term of the surface free energy of the alignment film is 1.0 mJ / m ２ The liquid crystal alignment properties fell below the standard. This is thought to be because the polyether-modified polysiloxane D contained in the alignment film had low polarity, resulting in weak electrostatic interaction with the cyano group, which is a polar group of liquid crystal compound B. In the transfer laminate for optical film of Example 9, the vertically aligned liquid crystal film did not contain a silicone-based surfactant, and neither the release properties nor the liquid crystal alignment properties met the standard. In the transfer laminate for optical film of Example 10, the content of the silicone-based surfactant in the alignment film was 1.5 parts by mass or more, and neither the release properties nor the liquid crystal alignment properties met the standard. In the transfer laminates for optical film of Examples 11 and 12, the content of the silicone-based surfactant in the vertically aligned liquid crystal film was outside the range of 0.3 to 4.0 parts by mass, and the liquid crystal alignment properties did not meet the standard.

[0076] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2024-196179, filed on 8 November 2024, the contents of which are incorporated herein by reference.

[0077] 10 Transfer laminate for optical film 1 Substrate 2 Alignment film 3 Vertically aligned liquid crystal film

Claims

1. A transfer laminate for optical films comprising a substrate, an alignment film, and a vertically aligned liquid crystal film in this order, wherein the polarity term of the surface free energy of the alignment film is 1.0 mJ / m ２ The above is true, wherein the content of the silicone-based surfactant in the alignment film is less than 1.5 parts by mass per 100 parts by mass of resin in the alignment film, and the vertically aligned liquid crystal film contains the silicone-based surfactant in a ratio of 0.3 to 4.0 parts by mass per 100 parts by mass of liquid crystal compound in the vertically aligned liquid crystal film, in a transfer laminate for optical film.

2. The transfer laminate for optical film according to claim 1, wherein the interface between the vertically aligned liquid crystal film and the alignment film is a peelable interface, and the peel strength when the vertically aligned liquid crystal film is peeled at a peeling speed of 300 mm / min is 1 N / 25 mm or less.

3. The transfer laminate for optical films according to claim 1 or 2, wherein the fluorine content in the orientation film is 0.1% by mass or less.

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